Method for distilling mineral oils



Marchzl, I933. E. w. BEARDESLEY ET AL METHQD FOR DISTILLING MINERAL OILS Filed Nov. 6, 1928 DUE 1A7- 1 ATTORNEY Patented Mar. 21, 1933 UNrrEo STATES PATENT OFFICE EDWIN W. BEABDSLEY AND DR'UE IvI. EVANS, OE

TEXAS CITY, TEXAS, ASSIGNOBS TO PETROLEUM CONVERSION GORPORATEON, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE METHOD FOR DISTILLING MINERAL OILS Application fiIed November 6, 1928. Serial No. 317,548.

5 is the purpose of this invention to provide a process and apparatus in which the distillation may be carried out to yield amaximum of the separated products and a minimum of loss due to decomposition; to provide for 0 an easier and more clearly defined separation of the components in the mixture, while avoiding the use of high vacua; and to provide a more accurate control of the operating conditions.

We achieve the foregoing and related ends while making use of a neutral gas as an aid to the distillation, such gas being caused to supply the required heat units and making possible the control of the rate of evapora- -tion as well as the pressure in the system by variation of the rate of flow of said gas therein. The use of a neutral gas in this way avoids the use of steam-which is disadvantageous since it must be gotten rid of in the condensers, such action disturbing the partial pressures then existing and causing constituents to drop out which would be desirable to keep in the vapor phase at such a stage. Furthermore, the condensation of steam requires a relatively large amount of cooling water and thus adds to the cost of the process. The use of neutral gases in the manner called for also has the advantage that it does away with external heating of the body of oil undergoing distillation and thus insures against overheating of portions of the oil, so heated from within. An important feature of the invention consists in providing an accurate means of heat control independent of the quantity of gas, and of oil to be distilled supplied to the distillation chamber. It will be apparent that the function of the gas is two-fold, (1) to provide the heat necessary for the distillation and (2) to regulate the rate of distillation by causing the production of so high avapor tension of the components undergoing distillation as to give arate of distillation which compares favorably with that under vacuum. 'While we do not limit our invention thereto we have found that the best way of regulating this temperature is to employ heat carrier gas at a temperature which having regard to the quantity used would heat the oil to a slightly higher temperature than that desired and then to regulate the temperature in the distillation chamber by adding thereto a controlled supply of liquid oil, preferably a portion of the residue withdrawn from the chamber and which has been cooled to a requisite degree. While the heat may be abstracted from the residual oil in a variety of ways, we have found it of particular advantage to accomplish it by transferring a regulated quantity of heat therefrom to the carrier gas on its way to the heating element. A further advantage of utilizing the residual oil in this manner is that by showering the same through the distillation chamber, it is caused to be intimately mixed with the heat carrier gas, thus making for the optimum distillation conditions.

A further advantage of the invention resides in the. fact that it lends itself readily to continuous operation.

Our invention will be best understood by reference to the following detailed description taken with the annexed drawing in which we have shown a plant embodying the invention in its preferred form.

In the drawing, 10 denotes a still into which oil preferably preheated at a separate pointin the system is introduced through a pipe 11. In order to effect the distillation of the oil, a. neutral gas conveniently of hydrocarbon origin is also introduced into said still through pipe 11a. The manner of heating this gas is optional but the best way known to us of accomplishing such heating is topass the gas through a hot blast stove as, for example, that designated by 12 which has previously been brought up to the requisite temperature, although we do not limit ourselves to the use of such stoves because at the maximum temperatures needed a tube heater is adequate. Such stoves which are well known, particularly in the blast furnace art, consist of a closed chamber filled with refractory checker work, provision being made to heat this refractory material up to a temperature somewhat above that desired for the gas to be heated and then for passing such gas over the re fractory material thus heated up. It is also customary to by-pass a portion ofthe cold gas as for example through pipe 115 and mix same with the heated gas by automatic means (controlling valve 116 for example) in such a manner as to produce a mixture of uniform temperature.

As has been stated, the heat-carrier gas which has thus been brought up to temperature, say from 600 to 1000 degrees F., is introduced in the still 10 through pipe 116: joining the stove 12 therewith where, due to the heat thereby imparted to the oil and to the low partial pressures of the vaporizing components of the crude stock, the latter except for the very heavy ends which are unsuited for lubricating purposes for example, is evaporated, and the produced vapor mingled with the carrier gas led from the still 10 through a pipe 14 to a rectifyin column 15. It will be understood that su cient carrier gas will be used so as to give the desired rate of evaporation without having to employ a reduced pressure of substantial degree. At the specified temperature of such gas this amount of carrier gas would be likely to overheat and crack the oil were not means provided for regulating the temperature within distillation chamber. \Vhile various means may be employed for thus regulating the temperature therein we prefer to remove continuously a portion of the residue in still 10 through a pipe 100, for example, pass same through a heat exchanger or cooler 101, thence through pipe 102 to storage receptacle 103. By means of pipe 104, pump 105 and pump 11 a regulated quantity of the oil may be circulated. Preferably a by-pass 106 around heat exchanger 101 is provided for accomplishing the regulation of heat extracted from such residue. By the means thus described the distillation temperature can be kept strictly below a predetermined value.

Column 15 is preferably either a bubble tower or one provided with filling material 16 as shown, affording an extended surface by virtue of which a large area of contact is provided between products admitted to the chamber through pipe 14, and the heavy fraction condensed out and also that which preferably is circulated through said chamber by means of a pipe 18, and pump 19. Storage of the condensate and oil circulated is had in a container 20, and return of the oil from the chamber 15 is effected through a pipe 21 through which the oil is led to a heat exchanger 22 and thence back to container 20 through a pipe 23. Thus by virtue of the large supply of liquid distillate which is circulated through the chamber 15 substantially uniform conditions as to temperature and vapor pressure are maintained therein, thereby making for uniformity of product from such chamber. Vapors remaining uncondensed from column 15 together with the carrier gas are led therefrom through pipe 25 into a second rectifying column 26 which is also provided with a similar circulating system including a pipe 27, pump 28, tank 29, return conduit 30, heat exchanger 31 and pipe 32. c In this column, however, the temperature is maintained at a somewhat lower value whereby oil of a somewhat lower boiling point is condensed out. The gases leave the column 26 through a pipe 35 and are then conveyed to a further column 36 which similarly is provided with a circulating system comprising pipe 37, pump 38, tank 39, return conduit 40, heat exchanger 41 and conduit 42. Likewise in this column a lower temperature prevails than the preceding chamber 26 whereby products of a still lower boiling point are obtained. From column 36, the gas and vapor mixture pass through a conduit 45 to a condenser 46, the liquid product f om such condenser being collected in tank 4 It will be understood that in each of the rectifying columns 26 and 36, the vapors therein will be subjected to the action of the respective condensates therefrom with the result that as in the case of column 15 already described, a high degree of uniformity of vapor and temperature conditions is maintained in each of said columns.

The carrier gas having been stripped of substantially all of its associated vapors in the condenser 46, leaves the tank 47, being propelled by means of a compressor or blower 48 through a conduit 49 through which it is ultimately returned to the stove l2. Preferably, the gas is preheated on its return travel in heat exchanger 101 through the heating space of which residue from the still 10 is passed as previously described. The oil entering the system preferably passes through a pipe 55 and then into heat exchangers 41, 31, and 22 in series and thence to pipe 11. In said heat exchangers, the temperature of the fresh charge is raised a number of hundred degrees. The products in the storage tanks 20, 29, and 39 are delivered from the system by means of pipes 56, 57, 58 respectively.

It will be understood that the system shown is illustrative only, and particularly that the number of rectifiers shown is arbitrary. It will be further understood that for the sake of explaining our invention, we have designated at different places in the drawing, temperatures which are likely to occur at such designated places without, however, intending to limit ourselves thereto as they will vary considerably depending process without their use.

upon the character of the stock and the results desired. A feature of the invention as previously pointed out is that the use of vacua is dispensed with inasmuch as results equal to or better than those obtained in vacuum stills may be had by the present Accordingly while it is possible to operate the present process under vacuum this ordinarily will not be done. Furthermore, the process lends itself to the use of pressures greater than atmospheric which in many cases are advantageous, particularly as regards the recovery of very light ends. Moreover the capacity of the system is increased at such increased pressures. The present invention is distinguished from a cracking process inasmuch as it is desired to use the products therefrom principally for lubricating pur- 'poses and accordingly it will be understood that conditions will be controlled so that a minimum of cracking results.

When the distillation process is carried out with asphalt-base oils, it is possible to separate a heavy flux-oil residue or an unblown asphalt residue in still 10, which residue is suitable for use directly or after blowing with steam and/or air as asphalt. This residue not having been subjected to cracking conditions and yet having all lighter constituents removed is particularly valufable.

It will be seen from the foregoing that we have devised a system of oil distillation which is susceptible to great accuracy of control. Such system also effects considerable economies as to heat by virtue of the heat exchange steps employed. Various changes may be made in the embodiment above described in detail without departing from the spirit of our invention or the scope of the appended claims.

We claim:

1. In the process of distilling oils containing a lubricating oil fraction, the steps which consist in maintaining a quantity of said oil undergoing distillation in a chamber, heating up an inert, substantially noncondensible heat-carrier gas to above a predetermined distillation temperature, mingling said gas with the oil undergoing distillation in a distillation zone, said gas containing sufficient heat units to accomplish the vaporizing of the desired components of the oil but insufficient to crack same, withdrawing the produced vapor together with the gas from said chamber and subjecting such mixture to condensing conditions, controlling the temperature in the distillation chamber by withdrawing a regulated quantity of the oil undergoing distillation therein, cooling same by heat interchange with a relatively cold gas which is to be used in said heating step in which its temperature is raised to above the distillation temperature and reintroducing at least a portion of the cooled oil back into the distillation chamber to control the temperature therein.

2, In a process of distilling oils containing relatively heavy fractions including those of the lubricating type to obtain oils of this type therefrom, the steps which conist in heating up an inert, substantially non-condensible heat-carrier gas to a tem perature above a predetermined distillation temperature, utilizing said gas to vaporize said lubricating fractions from said oil by mingling the gas and oil in a distillation zone, the quantity of said gas being somewhat greater than that just necessary to vaporize the desired fractions of the oil but. insufficient to craclrthe oil, withdrawing a portion of the liquid oil from the distillation zone, cooling a requisite portion thereof and re-introducing said cooled portion back into the distillation zone to control the temperature of distillation, and subjecting the vaporized fractions to condensing conditions to separate out the ones desired.

3. In a process of distilling oils containing relatively heavy fractions including those of the lubricating type to obtain oils of this type therefrom, the steps which con sist in heating up an inert, substantially non-condensible heat-carrier gas to a temperature above a predetermined distillation temperature, utilizing said gas to vaporize said lubricating fractions from said oil by passing the gas upwardly in contact with the liquid oil in a distillation zone, the quantity of said gas being somewhat greater than that just necessary to vaporize the desired fractions of the oil but insufiicient to crack said desired fractions, withdrawing a portion of the liquid oil from the distillation zone, cooling a requisite portion. thereof and reintroducing said portion back into said distillation zone in the form of a spray or shower above the liquid level therein whereby to control the temperature of the distillation and toy afford increased gas and liquid contact, and recovering from the vaporized portions said lubricating fractions.

4. In a process of distilling oils containing relatively heavy fractions including those of the lubricating type to obtain oils of this type therefrom, the steps which consist in heating up an inert, substantially non-condensible heat-carrier gas to a temperature above a predetermined distillation temperature, utilizing said gas to vaporize said lubricating fractions from said oil by mingling the gas and oil in a distillation zone, the quantity of said gas being somewhat greater than that just necessary to vaporize the desired fractions of the oil but insuflicient to crack the oil, withdrawing a portion of the liquid oil from the distillation zone, cooling a requisite portion thereof and re-introducing said cooled portion back into the distillation zone to control the temperature of distillation and fractionally condensing the vapors produced by conducting the mixture of vapor and gas to a condensing zone, there withdrawing a portion of the condensate, cooling same and re-introducing a definite portion of same back into the vapor space of said condensing zone whereby to separate out a definite fraction from said vapor.

5. In a process of distilling oils containing relatively heavy fractions including those of the lubricating type to obtain oils of this type therefrom, the steps which consist in heating up an inert, substantially non-condensible heat-carrier gas to a temperature above apredetermined distillation temperature, utilizing said gas to vaporize said lubricating fractions from said oil by mingling the gas and oil in a distillation zone, the quantity of said gas being somewhat greater than that just necessary to vaporize the desired fractions of the oil but insufiicient to crack the oil, withdrawing a portion of the liquid oil from the distilla tion zone, cooling a requisite portion thereof and re-introducing said cooled portion back into the distillation zone to control the temperature of distillation, passing the mixture of gas and vapor from said distillation zone through a series of condensing zones, each maintained at a lower temperature than the preceding, collecting distillate from each of said zones, passing the oil entering the system to indirect thermal contact with said withdrawn portions whereby to cool same and heat the oil, and re-introducing portions of said cooled portions back into the respective zones from which they were taken whereby to control the temperature conditions in each of said zones, and passing the thus heated entering oil to said distillation zone.

In testimony whereof we have affixed our signatures to this specification.

EDWIN lV. BEARDSLEY. DRUE M. EVANS. 7 

